Station selecting system



Oct?, 26, 1943. J. F. KEITHLEY ET AL STATION SELECTING- SYSTEM Filed oct. 25, 1941 ATTORNEY Patented Get. 26, i943 irss'mrssy Tsui sri s'rA'rroN sensoriale; srs'rinr Application @ctober 23, 1951, Serial No. 416,164-

v(ci. ris- 2) 4 8 Claims.

This invention relates to telegraph apparatus and systems andparticularly to a station selector system for placing two or more Vstations of a telegraph system including a plurality of stations in intercommunicative condition under the control of any one of the stations.

The invention represents an improvement .over

station selector systems heretofore known and particularly of the type shown in Patent 2,152,016, granted March 28, 1939, to W. J. Zenner. r

According to the disclosure of the Zenner patent each of a plurality of stations on a telegraph line is provided with a key for opening the line circuit for a predetermined minimum interval of time and each station responds to the opening of the line circuit by the starting of the operating motor of the printing telegraph set at that station. The attendant at the` station at which the motor starting function was initiated Vthen transmits the call signal of the calling station which is `recorded at all Vof the stations, and which is effective at the calling stationto condition the motor starting apparatus to lremain operated, and thereafter transmits the call signal or signalsof the called station or stations, which are recorded at all stations and which condition the motor starting apparatus to remain operated atV the respective called stations. Thereafter the attendant' transmits a common disabling signal which is effective at all uncalled stations to shut down the operating motor and to disable the transmitter and the call initiating line circuit keys, but the selector magnets at the uncalled station remain under the control of the telegraph line and chatter in response to signals not intended for those stations.

.an object of the present invention is to enable a station to distinguish with certainty between an open line circuit condition incident to the initiation of a call and` Yan open circuit condition occurring incident to normal signal transmission or fortuitously.

Another object of the invention is to condition a calling station to remain in operation as an incident to the initiation of a call and without necessitating the transmission of the call signal of `that station. g

A further object oi the invention is to isolate completely the signal transmitting and signal receiving apparatus of anuncalled station from control of or control by the communication line circuit. v

In accordance with the preferred embodiment of the invention, each of `the stations associated with a .telegraph line circuit has', in addition to the transmitting contacts and selector magnets or line relay, a pair of normallyclosed contacts which, upon being opened,`requires an interval representing a considerable number of permutation code combinations to close, and an instan taneously responsive relay, all of these elements being included in the line circuit. The relaycontrois a normally energized relay which is slow to release, the release time being longer than one permutation code combination, but considerably shorter than the interval required for the normally closed contacts in the line circuit to close after being opened. Theslow-release relay, upon releasing, controls the energization `of a very slow-operating relay which is timed to opcrate just before the line circuit contacts reclose under the control of their retarding device. The slow-operating relay at each station operates to eiect the energization of` a relay which completes the circuit for the operating motor at the station, and the motor control relay remains energized over a provisional holding circuit. Each of the normally closed `line circuitcontacts has ganged thereto apair of normally open contacts which, upon the opening of the line circuit contacts ata station, "become closed to establish, at that station only, a holding circuit for the motor control relay in parallel with the provisional holding circuit.

'Following theV rcclosure of the line circuit at the calling station, the attendant transmits one or more code combinations` representing one or more stations being called. At those stations to which the transmitted calling code signals are assigned, contacts controlled by thev selector mechanisms are closed to control the establishment of holding circuits for their motor control relays in parallelwith the provisional holding circuits. All ofA the stations record all of the station selecting codes but those not represented by the calling codes do not establish` additional holding circuits for their motor contro-l relays. Following the transmission of the station selecting code -or codes, the callingV station transmits a cut-oir" code. All of the stations record this code and at all stations the provisionalholding circuit for the motor control relay is interrupted. At the calling ,and called stations the `supplementary holding circuits maintain those relays operated to hold their stations in operative condition but at the uncalled stations the motor `control relays are released and the stations are shutdown. Incidentto the shutting down of the uncalled stationstheir la, Y 2,332,645

transmitters, recorders and normally closed line contacts are shunted out of the line circuit so that they can neither transmit nor respond to signals.

For a complete understanding of the invention reference may be had to the following detailed description to be interpreted in the light of the accompanying drawing in which the single figure is a schematic circuit view showing three stations in accordance with the present invention associated with a telegraph line circuit,

tWo stations being shown in full detail, and a' third being represented symbolically.

Referring now to the drawing, the letters A! Band C represent three stations associated with a telegraph line. It will be understood that as many more stations as desired up to the number of calling codes available, say 26, may be included in the line circuit and other stations may be operatively associated with the lineV circuit shown through suitable repeaters. The line'circuit is indicated bythe reference numeral I I and at each of the stations A, B and C, the line circuit includes permutation code transmitting contactsI I2, recording printer selector magnet, or line relay (shown as magnet) I3, normally closed line circuit contacts lI4 and a relay I6. The transmitting contacts I2 may be either keyboard controlled or tape controlled. The normally closed contacts I4 are arranged to beopened manually, and apparatus is provided to delay the closure of these contacts for an interval representing a considerable number of permutation code combinations. The delaying mechanism may be a spring driven governed mechanical device such as a clockwork mechanism, or may be a dashpot mechanism as indicated by the reference numeral I?.

The purpose of the delayingl device I'I is to prolong the open condition of contacts I4 beyond any interval of open line condition likely to be encountered in normal signaling and beyond any interval that the line II is likely to be fortuitously or accidentally open. In accordance with one embodiment of the invention, the delaying device Il has been arranged to introduce a delay interval of eightseconds inthe closure of contacts I4. In ordinary telegraph transmission, a normal break signal, which is accomplished by opening the line, is usually not longer than two or three seconds duration, so that a delay oi eight seconds would be ample to guard against operation of the station selecting mechanism in response to any signaling condition impressed upon the line I I other than by the contact I4.

As previously stated, the signaling line II includes at each station a relay I8 which is instantaneously responsive to signaling conditions in the line and which is energized when the line circuit II is closed to hold its armature in engagement with its front contact. The front contact of relay IB is connected through resistor l5 to ground and the armature of relay I6 is connected to one terminal of the winding of a slow-release relay I8, the other terminal of which is connected to grounded battery I9. Since relay IB is energized when the line II is in the steady marking condition, it holds the relay I8 energized and the relay I8 has no front contact. The retardation in the release of relay I8 is suiicient to prevent the relay from responding to the operation of instantaneously responsive relay I5 as it follows signaling conditions in the line I I. The relay I8 will release only after the relay I6 has remained deenergized for an interval substanf before the contacts I4 reclose.

tially greater than the longest spacing signal normally encountered during the signaling.

The armature of relay I8 is connected to grounded battery I9 and the back contact of the relay is connected to one terminal of a very slow operating relay 22, the other terminal of which is connected through resistor 23 to ground. The interval which the relay 22 requires to operate is such that when the line contacts I4 enter into their restoring cycle under the control of delayingfdevice I1 therelay 22 will be operated just In accordance withone embodiment of the invention the characteristic'of Arelay 22 is such that an interval l of about six seconds intervenes between the closure of the energizing circuit of relay 22 and the operation of its armature. Since, as previously stated, in this embodiment of the invention the delaying device Il is arranged to introduce a delay interval of about eight seconds in the closure of contact I4, it will follow that the releasing time for slow-release relay I8 is somewhat less than two seconds.

The front contact of relay 22 is, connected to, grounded battery 2| and the armature is connected to one terminal of the winding of relay 24, the other terminal of which is connected through resistor 26 to ground. The left-hand armature of relay 24 is operable between a back and a front contact and the front contact is connected to one terminal of the winding of relay 2l, the other terminal of which is connected through resistor 28 to ground. The left-hand armature of relay 24l is connected to grounded battery Z9. The outer left-hand armature of relay 2'! cooperates with a grounded iront contact and the armature is connected to oneterminal of an operating motor 3| for the printing telegraph set and to one terminal of an indicator lamp 32. The other terminalwof motor 3l and lamp 32 is connected to grounded battery 33 which serves as a source of power for the motor and the lamp. l

The inner left-hand armature of relay 2l' cooperates with a back contact only and is connected tact establish a shunt across the selector magnet I3 and transmitting contacts I2 so that the se- I lector magnet I3 will beincapable of responding to signals on the telegraph line l I and the transmitting contacts I2 will be incapable of impressing Signals on the telegraph line. The righthand armature and front contact of relay 2l establishes a provisional holding circuit for the relay from grounded resistor 28 through the winding of relay 27, front contact and right-hand armature of the relay, conductors 34 and 3G, normally engaged lower and middle springs of a set of contact springs 3l, conductor 38 and normally closed contact springs 39 to grounded battery 4I.

Ganged to the normally closed pair of contacts I4 so as to be closed when the contacts. I4 are opened, is a pair of normally open contacts 42, one of which is connected to grounded battery 43 and the other of which is connected through conductor 44, conductor 46, outer left-hand armature and back contact of relay 4l, conductor 48, ixed contact and movable make-beiore-break When the relay '2l is in deenergized condition, the inner left-hand armature and back conl front contact controlled by the inner leftehandA armature of relay t9, and winding of vrelay 4t. through resistor 5I to ground.

Upon the opening of contacts Iltmanually at station A, for example, the contacts 4t2' att that station are closed `to complete the energizing circuit for the relay de. When the` relay :is becomes energized, its inner left-handarmature engages the movable front contact before that contact is disengaged from the stationary contact and corn-` pletes a holding circuit for the relay 49 from ground through the resistor "5I, Winding of relay a9; movable front contact and inner left-hand armature of the relay, conductor 52,' conductor inner rightehand back contact and armature of relay il to grounded battery 53.1andin parallel. therewith through conductor 54 and `lefthand backco-ntact and armature of relay 2&- to grounded battery 2li.

When the normally closed contacts it are opened manually the relay It. responds instantaneously to the open or spacing condition of telegraph line l! and releases its armature, thus interrupting the energizing circuit for the sloW- release relay lli. The closure of contacts i2 accompanies the opening of: contacts I whereby energizing circuitl for relay I9 is completed and the relay becomes energized and held through its malre-before-break contact associated With the inner left-hand armature to the batteryconslow-release relay It completes the energizing l circuit for the relay 27. and the relay 22 becomes energized just before the contacts it at station A reclose if those contacts. have been permitted to enter their restoration cycle immediately upon being opened andhave not been held manually for an appreciable interval. It Will be understood that if the contacts, Hl areheld openrnanually ior an interval, the relay 22 at each station 'will become energized a correspondingly greater interval before the reclo'sure of contacts III than if the contacts M had been released from manual control immediately upon moving them to' their fully open position. This Will have 'n undesirable eilect since it'isnecessary only that a minimum delay interval beforethe reclosure of contacts I be provided and this minimumdelay is aorded bythe delay device I'I.

The momentary operation of relay 22 at each station results in completion of the energizing circuit for relay 2li which becomes momentarily energized and at its left-hand armature removes one of the holding circuit battery connections for the relay d8 and completes the energizingcircuit for the relay Z'I which becomes held over the provisional holding circuit including the contacts STI 3Q et all stations and over, an additional holding circuit afforded by the inner right-,handv armature and iront contact of relay dfinand grounded battery 55 at station `A due to the fact lthat that relay is now energized. 'The relay 2l starts themotor 3i and lights the lamp32 at each. station by means of its outer left-hand armature and front contact and removes the-shunt across the selector magnet and transmitting contacts `at eachV station by means of yits:innenleft-hand;ar-

mature 'and backl contact so that all of the stations on line II arek now in operation and are conditioned to respond to permutation code signalsjon the telegraph line I I and to impress signals on `that line by their` transmitting contacts Following the reclosure of the contacts Hl the telegraph line I I is in condition for the transmission of signals indicative of the station or stations to be selected for participation in interccmmunication. Since station A has been assumed to be the calling station, it is assumed that station A will transmit the station selecting signals. Accordingly, the attendant at station A. operates transmitting contacts I2, as by operation ofa keyboard transmitter mechanism, to transmit a signal to select a station which, for the present purposes, will be assumed to be the station C. It should be noted that at all of the stations the relays 22 and 2t become deenergized and the slow-release` relay I t became energized following the reclosure of contacts M. Thus the relays 2li at all stations are deenergized and the motor controlling relays 2l are held energized by their holding circuits.

-All of the stations respond to the call signal by recording the character corresponding to the code, .and the station C responds to its call signal by selecting a selectable member (il which is operated to close momentarily the normally open contacts 62. One of the contacts b2 is connected to grounded battery li-I andthe other .is connected over conductor 63 and then over the previously traced path including conductor 5, outer left-hand armature and back contact of relay lll, conductor 58, stationary contact and movable iront contact controlled in make-beforebrealr manner by the inner left-hand armature oi relay lid, winding of relay Il@ and resistor 5I to ground.` Thus the Vrelay iii at station C becomes energized in response to the closure of contacts 52 and a holding circuit for that relay is established in the same manner as in the previousdescription of the energization of relay i9 at station A. At no other station does the relay dit becomeenergized in response to the transmissionl of the call signal for the station C since the selectable member @I at other stations is not responsive to that code, but is responsive only to ther call signal of the station With which it is associated. The provision oi the contacts lli? operated in conjunction with the opening of the contacts Il eliminates the necessity for a calling station to transmit own codein order to effect the energize-tion of its relay 4S, since that relay becomes energized directly through a circuit completed by the contacts d2.

At each of the stations there isa conductive path` `brancl'ling from the conductor i8 and includingtheconductor fifi, Winding of an elec- 'nromagnet t@ and resistor Eil' to ground. At each of the stations the electromagnet tl has its armatureI connected. mechanically to one of the key levers {il}V oi the keyboard transmitter mechanism at that station and the key lever is a dii"- ierent one at each station for eecting the transmission of diierent codes from the stations. Uponthe energization of the relay il@ at any station, Whether by operation of the contacts i2 or by operation of the selector controlled contacts 52, the branch circuit including the electromagnet 55 isv also completed to effect the energization of the magnet 6G. and the operation of -itsrV associated keylever. In the case of operationof the magnet 'through the contacts 42 in connection with the initiation of a call the operation of the keyboard transmitter does not result in the transmission of a code signal on the telegraph line l! because the line 'is then open at the contacts I4 and the relay 2l' has not yet become energized so that the shunt across the transmitting contacts provided by its inner left-hand armature and back contact is complete. When the operation of magnet 66 is effected through th'e contacts 62, as in the Vpresently contemplated case of station C, the telegraph line is at this time closed and the shunt across the transmitting contacts has been removed, so that a signaling code particular to the station C and serving as an answer-back is impressed upon the telegraph' line I I. This answer-back code operates the telegraph recorders at all stations on the line including the station since the motors 3i at all of the stations are in operation and the shunt around the selector magnet at each of those stations is open at the inner left-hand armature and back contact of relay The response of the receiving printer at the station A to the answer-'back code transmitted from the station C indicates to the attendant at station A that station C is in readiness to receive telegraph signals. If the answerback code is the same as the calling code for any a large number of stations, as for eX- ample may be accommodated by the system, whereas if each station has different call and answer-back codes, such as C for being called and D for answer-back, the number of stations that may be accommodated is reduced, since a code may not serve as the call for one station the answer-back for another, otherwise the answer-back signal would select the station having that code as its call.

Following the receipt of the answer-back signal from station C the next step is to disqualify all other stations from participating in the intercommunication between stations A and C. This is accomplished by the operation of the transmitter l2 at station A to transmit a signaling code to which the selectable members 1I at all of the stations in the system are responsive. lectable member 1i engages the middle of the three contact springs 31 to move the middle spring out of engagement with the lower spring and into engagement with the upper spring, the disengagement of the middle spring from the lower spring and the engagement with the upper spring being momentary, after which the middle spring returns to engagement with the lower spring. The disengagement of the middle spring from the lower spring interrupts the provisional holding circuit for the motor control relays 21 at all stations. Since a supplemental holding circuit for the relays 2l' at the stations A and C has been established by the inner right-hand armature and front contact of the relays 49, the relays 21 at those stations will not be released but at all other stations, where only the provisional holding circuit is holding the relays 2l energized, the relays will be released to open the circuits of motor 3i and lamp 32 at those stations and to restore the shunt across transmitting contacts I2 and selector magnet I3.

The engagement of the middle contact 3l with the upper contact results in the completion of a circuit from battery il through normally closed contacts 3d, conductor 38, middle and upper contacts 31, conductor 12, winding of relay 41 and The seresistor 13 to ground. Thus, the relay 41 becomesv motors the deenergized relays 49 cannot becomev energized in response to signals occurring in the message to which the selectable members'II at those stations are responsive, even if the motors ai; those stations should be restarted unauthorizedly by attendants at those stations through tampering with the apparatus and, more importantly, so that the relays 49 cannot become energized at the excluded stations through the operation by attendants at those stations of call initiating contactsv I4 and 42, `it being remembered that the relays 49 at each station are normally energizable by operation of the manually operable contacts 42 as well as by the signal responsive contacts 6i. At the stations A and C, the opening of the conductive path at the outer left-hand armature and back contact of relay 41 has no elect because that path is open at the stationary one of Vthe make-before-break contacts of relay 49 due to the fact that the relay is held energized by its holding circuit.

At the inner right-hand armature of relay 41', battery connection is transferred from one of the holding circuits for therelay 49 at leach station to a busy lamp 14 which has one of its terminals connected to the inner right-hand front contact of relay 41 and the other side connected through resistor 16 to ground. Thus the busy lamp 14 becomes operated at all stations. The interruption of the holding circuit connection to battery 53 has no effect at any of the stations because at the excluded stations the relay 49 has not beenenerl gizefd and no holding circuit has been established and vat the participating stations A and C, the parallel' holding circuit is maintained'at the lefthand armature and back Contact of relay 24 which at this time is deenergiz'ed.

At the outer right-hand armature and front f contact of'relay 41 a holding circuit for that relay is established from grounded resistorv 13 through the winding of the relay, outer'righthand armature and front contact, vconductor 11, conductor 13, and right-hand armature and back contact of relay 24 to grounded battery 15. A parallel and supplemental holding circuit path for the relay 41 extends from the junction of conductorsk 11 and 18 over conductor 19 through the outer right-hand front contact and armature of relay 49 to groundedvbattery 56, which supplemental holding circuit is established only at the stations at which the relay 4,9 is energized which, in the present description is presumedA to be the stations A and C.

At the inner left-hand armature and front` contact of relay 41, a conductive path is extended from one side of the line opening contacts I4 through conductor 82, inner left-hand front contact and armature of relay 41, conductor 83, to the outer left-hand armature of relay 49. At excluded stations, the relay t9 is kdeenergized and the outer left-hand armature engages its back contact which is connected by conductor 84 tothe other side of contacts I4 at a point online I I between' the normally closed contacts I4 and the line relay I 6, which point is on the remote side of contacts I4. relative to the selector magnet I3.

Thus the shunt which was placed across :the

transmitting contactsl2 and selector magnet 'I3 by the deenergized relay 2l at excluded stations, is extended to include the normally closed contacts I4 so that an attendant at an excluded station cannot interfere with signal transmission on the telegraph line ll, nor effect the starting of the motor ill at that vexcluded station and Aall other excluded stations by operation of the normally closed contacts it. d

The system is now conditioned for Aintercommunication between the stations which1 haveibeen included for participation in Asuch communication. At those stations the relays 2l, lll and lle are energized and held through holding circuits, the motors 3l are in operation, the lamps lil are illuminated to indicate that'the telegraph line i l is in busy condition and the lamps 32 are illuminated to indicate that those stations are included for participation in the message transmission. At excluded stations thetrelays il are energized but the relays ill and il@ are deenergized and the motors 3l are not operating. The lamps 'Hl are illuminated at those stations to indicate that telegraph line ll is in busy condition but the lamps t2 are deenergized to indicate that those v stations have been excluded from participation in the message transmission'and reception. Message transmission is accomplished by the operation of transmitting `contacts l2 and messages are received by the operation of the selector magnets i3. The inclusion in the message material of signals which, in addition to representingcharacters to be recorded, may also have the function of selecting the selectable membersl at the severalstations, will select the selectable members 6i at the participating stations and cause the closure of contacts B2 but this will have no efi'ect at those stations since the conductive path which extends from the contacts ti for energizing the relays t9 and, it may be added, the conductive path from the normally open manually operable contacts d2, in parallel with the contacts t2 is interrupted at the outer left-hand armature and back contact oi relay il which is energized at all stations.

When message transmissionvhas been concluded, any one of the stations which participated in the message ytransmission imay initiate the shutting down of all oi thestations, this `being accomplished by the opening of the normally closed contacts it in the same manner as thatV employed for starting the station selecting operation. T'ne accompanying closure of normally closed contacts lil has no effect because relay fil is energized, thereby opening the energizing circuit of relay :t9 at the outer left-hand armature and contact of the relay il. Just before the reclosure oi contacts i4 under the control oi delaying device il, relay 22 operates and` cornpletes the energizing circuit for relay 2d., At its right-hand armature the relay'2l interrupts the holding circuit for relay l vat all stationsexcept those which were included in the message transmission. This does not ,affect the holding circuit for relays @l established at the outer `righthand armature and iront contact of'frelay laat those stations. However, the left-hand armature of relay 2li in moving out of engagement with its baci: contact interrupts the only holding circuit ior the relays 49 at the participating stations that was effective, since the supplemental holding circuit aiiorded by battery `at the'left-hand inner armature of relay il wasinterrupted when the relayll'l became energized. :Accordinglmthe relay i9 releases,-and at-its outer right-hand i stations but by this time the left-hand armature of `each relay 24 has moved into engagement Withits front contact Vthereby completing the energizing circuits for the relays-2l at all stations so that they motors 3l at the stations which participated in the intercommunication remain in operation and those at-theexcluded stations are restarted. The-release of the relays M removes at the excluded stations theshunt across Ithe normally closed contacts l4and the energization oi `the relays `2l' at those stations removes the shunt across the transmitting contacts l2iand selector magnets vI3 so that all stations are now in full communicative condition with respect to telegraph line Il. The system is thus restored to the condition which existed following thereclosure of contacts-llifat the calling station when the station selecting operation was begun, with the exception that none of the relays 49 is energized because the'relay 2li at the stationwhich operated the contacts i4 to initiate theshutting down of the stations was held energized by its holding circuit at thetime that the contacts -llZ were closedfand the relayllg was notireleased to restore its normal energizing circuit until vafter contacts i2 had reopened.

As previously stated the provisional holding circuits for the relays 2l, through which the relays are at this time'held` energized, `include the normally closed contacts 39. These contacts are controlled by a selectable member 8S which is responsive at all stationsto the same signaling code combination, which is adisconnect signal. At this time any station on the telegraph line i l may transmit the disconnect signal by means of its transmitting contacts l2, but itis assumed that the station which initiated the disconnect operation by the operation `of normally closed contacts I4 will transmit the disconnect signal. Accordingly, that station transmits'the disconnect signal and at every station onthe telegraph line Il the selectable member 86 is selected and is operated to open momentarily the contacts 525i, thus interrupting the holding circuitfior the motor control relays -`2l. These relays releaseat all stations and interrupt the circuits overnwhich power is supplied to `motors I3! and lamps f32'so that the motors stop and the lamps are `extinguished. At its left-'hand inner armature and back contact the relay'l at-each station restores the shunt across the transmitting contacts l2 and selector magnet vI3 and 'in this Way each station is restored to `the `initial condition vwith the driving motor idle, both indicator lamps extinguished, and all lrelays --released except the slow-release relay i3 andthe line relay l5.

Although a particularembodiment of `the invention hasbeen shown in the drawing andd'escribed in the accompanying specification; itV will be understood that the invention is'not limited to such speciiic embodiment but 'is capableoi modification, rearrangement and substitution of parts and elements without departing from Ythe spirit of the invention-and within the scope of the appended claims.

What is claimed is:

1. In a telegraph system, a normally closed communication circuit, a plurality of stations associated with said circuit, a printing telegraph set at each station,ia normally disabled operating motor for each telegraph set, means at each station for interrupting said circuit and for reclosing said circuit after an intervallonger than a maximum normal interruption during signaling and longer than fortuitous interruptions, means controlled by `said circuit interrupting means and operable just before the reclosing of the circuit for starting the operating motors at all stations, signal controlled means at each station responsive to a signal individual to such station for conditioning said motor starting means to remain operated, vand means at each station responsive to a common signal `for disabling the motor starting means at all stations not so conditioned and for excluding the printing telegraph set at the station having disabled motor starting means from said communication circuit.

2. In a telegraph system, a normally closed communication circuit, a plurality of stations associated With said circuit, a printing telegraph set at each station, a normally disabled operating motor for each telegraph set, manually operable means at each station for interrupting said circuit, means for controllingr vand delaying the reclosing of said circuit by said interruptingV means for an interval longer than a maximum normal interruption during signaling and longer than fortuitous interruptions, delayedly operable means controlled by said circuit interrupting means for starting the operating motor at all stations just before the reclosing of the circuit under the control of said delaying means, signal controlled means at each station responsive to a signal individual to such station for conditioning said znotor starting means to remain operated, and means at each station responsive to a common signal for disabling the motor starting means at all stations not so conditioned and for excluding the printing telegraph set at the stations having disabled motor starting means from said cor munication circuit.

3. In a telegraph system, a normally closed communication circuit, a plurality of stations associated With said cir-cuit, a printing telegraph set at each station, a normally disabled operai;vm ing motor for each telegraph set,I manually operable means at each station for interrupting said circuit, means for delaying the reclosure of said circuit by said interrupting means for an f interval longer than a maximum normal interruption during signaling and longer than fortuitous interruptions, a rst operating means controlled by said circuit interrupting means and operable during the operation of said delaying means, a second operating means controlled by said first operating means and operable just before the end of the interval introduced by said delaying means, means controlled by said second operating means for starting the operating motors at all stations, signal controlled means at each station responsive to a signal individual to such station for conditioning said motor starting means to remain operated, and means at each station responsive to a common signal for disabling the motor starting means at all stations not so conditioned and for excluding the printing telegraph sets at the stations having disabled motor starting means from said communication circuit.

4. In a telegraph system, a normally closed communication circuit, a plurality of stations associated With said circuit, a printing telegraph set at each station, a normally disabled operating motor for each telegraph set, means at each Cil station for starting the motor' at V'said' stations, -sloW operating relay means for .controlling lsaid motor startingmeans, relay means included in said circuit at each station and instantaneously responsive to signaling conditions therein for controlling said slow-operating relay means, and means interposed between said slow-operating relay means and said instantaneously responsive relay means for rendering the control of the. latter over the former indirect to ydisqualify said slow-operating relay means from operating on cumulative elects arising out of signal responsive operation of said instantaneously responsive relay means. l

5. In a telegraphsystem, a normally closed communication circuit, a plurality of` stations associated withA said circuit, a printingtelegraph set at eachstation responsive to equal length permutation code signals, a normally disabled operating motor for each telegraph set, means at each station for interrupting said circuit, means for delaying the reclosure of said circuit by saidinterrupting means for an interval representing a considerable number of equal length permutation code signals, instantaneously responsive relay means included in said communication circuit at each station, `slow-release relay means controlled by said instantaneously respon-y sive relay means requiring an interval exceeding that of one permutation code and less than that introduced by said delaying kmeans to release, slow-operating relay means controlled by said sloW--release relay means and operable just before the reclosure of said circuit under the control of said delaying means, means controlled by said slow-operating relay means at each station for starting the operating motor at Suchstation, signal controlled means at each station responsive to a signal individual to such station for conditioning said motor starting means to remain operated, and means at each station responsive to a common signal for ldisabling the motor startv ing means at all'stations not so conditioned, and for excluding the printing telegraph set at the stations having disabled motor starting means from said communication circuit.

6. In a telegraph system, a normally closed communication circuit, a plurality of stations associated with said circuit, a printing telegraph mutation code signals, a relay in said circuit at each station instantaneously responsive to signaling conditions in said circuit, a slow-release relay controlled by said instantaneously responsive relay requiring an interval to release in excess of that represented by one permutation code signal and less than half of the interval introduced by said delaying means, a slovvoperating relay controlled by said slow-release relay and operable just before the end of the interval introduced by said delaying means, means controlled by the slow-operating relay at all stations for starting the operating motors at said stations, signal controlled vmeans at each station responsive to a signal individual to such vstation for conditioning said motor starting means to remain operated, and means ateach station responsive to a common signal for disabling the motor starting means at all stations not so conditioned and for excluding the printing telegraph set at the stations having disabled `motor starting means from said communication circuit.

7. In a telegraph system, a normally closed communication circuit, a plurality of stations each having signal transmitting means and signal responsive means associated With said communication circuit, means normally effective to disable said signal transmitting means and said signal responsive means, a normally disabled operating motor at each station, means at each station for interrupting said circuit and for reclosing said circuit, means controlled by said circuit interrupting means for starting the operating motors at all stations and for rendering said disabling means ineiective whereby to qualiiy said signal transmitting means and said signal responsive means to loev operative, signal controlled means at each station responsive to a signal individual to such station for conditioning said motor starting means to` remainvoperated, and means at each station responsive to a common signal for disabling the motor starting means at all stations not so conditioned whereby the disabling means for said signal transmitting means and said signal responsive means is again rendered effective and for also disabling said circuit interrupting means.

8. In a telegraph system, a normally closed communication circuit, a plurality of stations each having signaltransmitting means 'and signal responsive means associated With said communication circuit, means normally shunting said signal transmitting means and said signal responsive means for rendering them ineffective, a normally disabled operating motor at each station, means at each station for interrupting said communication circuit and for reclosing said circuit, means controlled by said circuit interrupting` means for starting the operating motors at all stations and for interrupting said shunting means, signal controlled means at each station responsive to a signal individual to said sta-` tion for conditioning said motor starting means to remain operated, and means at each station responsive to a common signal for disabling the motor starting means at all stations not so conditioned whereby to reestablish said shunting means and for extending said shunting means to include and disable said circuit interrupting means.

JOSEPH F. KEITHLEY.

GEORGE J. KNANDEL. 

